Bituminous dispersions for coatings or coverings and a process of preparing them



' the like, as coatings for sheets, roofs, for bituminous linings oftubes, walls, shafts, chimneys or Patented ay re, 1936 TES NT OFFICEEARING THEM Karl Daimler, Frankfort-on-the-Main-Hochst, Germany,assignor to 1. G. Farbenindustrie Aktiengesellschaft, Gery Frort on theMain,

No Drawing. Application January 2, 1931, Serial No. 506,316. in GermanyJanuary 30, 1939 3 illaims.

I have found that dispersions for coatings or coverings can be preparedby mixing high-melting bitumen and low-melting bitumen in the form of astable'dispersion at a temperature which is below the softening point ofthe low-melting bitumen. These dispersions contain high-melting bitumenand low-melting bitumen side by side, i. e., the particles of thedifferent bitumens are not combined by dissolution or melting together.During the storage of the dispersion the dissolution of the particles ofhigh-melting bitumen in those of low-melting bitumen is prevented by thedispersion Water so that no uniform dissolution product of an averagemelting temperature is produced. g

These dispersions are used, if required mixed with comminuted stone,such as chips, sand and ,for the preparationof bituminous mortar masses,

riation of temperature. When preparing road coverings one can proceed inthe usual manner; either by applying the asphalt dispersions on theroads and subsequently covering them with chips or sand or by mixingfinely broken stones, chips and sand in a mixing machine withltheyasphalt dispersion and spreading the mixed mass in a thickness ofseveral centimeters on the road and compressing it either by rolling orramming.

When the dispersions are allowed to dry, the particles keep theircharacteristic feature, this being a surprising fact. The particles alutinate with each other but they do not mix in the sense of yielding auniform solution. A coating or a bituminous film produced from thesemixed dis-= persons can be imagined as a mosaic wherein the low-meltingparticles fulfil their function as an elastic adhesive even in thesevere cold whereas the high-melting particlesact nearly as an inertfiller constituent. in summer these high-melting particles prevent thecovering running too much and getting soft, as the particles hen showthe highest degree of elasticity ,adhesiveness when the low-meltingparticles have already become liquid. Even in midsummer a suficientviscosity of the cementing cover of the mineral material is thusguaranteed.

It may be particularly advantageous to use mixed dispersions whichcontain such dispersing agents as are no longer affected or redissolvedby water after the dispersion has been allowed to dry once. It maybecome important for the process whether the dispersions which are to beunited contain the same or difierent dispersing agents and at which timethe dispersions are united whether before or while being worked up.

During the manufacture and storing of the mixed dispersions one mustproceed in such a. manner that a mixing of the low-melting with thehigh-melting bitumen is excluded. Temperatures above the softening pointhave likewise to be avoided as much as possible. The process is,therefore, preferably carried out as follows: The ready made coldasphalt with low-melting bitumen is mixed at ordinary temperature withready"made cold asphalt which is prepared from high-melting bitumen.While observing particular precautions and very low dispersingtemperatures the two bituminous substances may be dispersed togethersimultaneously in the same vessel without their dissolving or mixingwith each other.

The following examples serve to illustrate the invention, but they arenot intended to limit it thereto, the parts being by weight:

(1'). 200 parts of a bituminous dispersion of 50 per cent strengthprepared from petroleum asphalt having a softening point according toKramer-Sarnow of 50 C.-60 C. are mixed at ordinary temperature with 100parts of a 50 per cent dispersion of petroleum asphalt. prepared frompetroleum asphalt of the softening point according to Krdmer-Sarnow of(1-30 C.

The product serves for painting gutters or for coating roofs which, ifthey are to be walked on, are subsequently covered with sand.

into 208 parts of a per cent paste of finely ground lignite containinghumic acid there are caused to run at a temperature of between 40 C. and50 C. the fused mass of 500 parts of petroleum asphalt having atemperature of 80 C. and a softening point according to Kramer- Sarnowof 50 C.-60 0., while vigorously stirring and adding 300 parts oi coldwater in such a manner that the temperature of the dispersion producednever exceeds 50 C. The mixture is then cooled to 30C. so that theparticles of the petroleum pitch melting at 50 C.-60 C. are always belowtheir softening point and are thus present in the dispersion in solidform surrounded by water. Into the dispersion there are caused to runthe fused mass of 500 parts of road making tar having a temperature ofabout 50 C. while cooling the impregnating vessel and vigorouslystirring, in such a mannerthat the content of the vessel does not riseabove 30 C. Partly simultaneously, partly after the addition of the tarthere are added 500 parts of cold water. During this method of workingthe road making tar is converted into very fine particles which aresurrounded from all sides by water and which, therefore, cannot beunited with the solidified particles of petroleum pitch likewisesurrounded by water. Even during the storage and use of these mixeddispersions the two kinds of bituminous components cannot be united witheach other, this being prevented on the one hand by the water-cover ofthe various particles, on the other hand by the temperature which isconstantly kept below the softening point of the petroleum pitch.

The mixed dispersion thus obtained is spread upon a well cleanedmacadamized road and well coated. The road is then covered with basaltchips. The process may be repeated several times, if required.

(3) A mixture containing 30 parts of finely ground chips (2-3 cm.), 30parts of chips (granular size 5-8 cm.),'30 parts of sand, 10 parts ofpulverized basalt, all products in the natural moist condition, isintimately mixed with 10 parts of the bituminous dispersion preparedaccording to Example 2. This mixture is particularlysuitable for thepreparation of mixed covers. For this purpose the mixture is poured uponthe road and uniformly spread by means of a rake and then compressed byrollers so as to form a layer having a thickness of 3-4 cm'.

I claim:

1. The method of insuring the binding actio 'of asphalt which is appliedas an asphalt emulsion to serve as a binder in the construction ofhighways, which method comprises incorporating in a hard asphaltemulsion an independent emulsion of a softer, solid, bituminous materialfluxible with said hard asphalt, and preventing the fluxing of thesofter, bituminous material with said hard asphalt whilepresent in theemulsion by means of a dispersing film which prevents coalescence untilthe emulsion has dried or has been broken, whereby a better binding iseffected when the emulsion is dried or broken than could be effected bythe use of a simple emulsion of the hard asphalt and the soft bituminousmaterial.

2. An aqueous asphalt emulsion consisting essentially of a hard asphaltin an aqueous phase in the form of rounded solid asphalt particlesseparated from the continuous aqueous phase by an interfacial film and alower melting solid asphalt likewise dispersed in an aqueous phase inthe form .of rounded particles separated from the continuous phase by aninterfacial film, the hard asphalt and the lower melting asphalt beingdispersed in the same aqueous phase whereby the interfacial films on thehard asphalt particles and the lower melting asphalt particlesrespectively prevent the fluxing of the hard asphalt with the lowermelting asphalt'prior to the breaking of the emulsion.

3. An aqueous asphalt emulsion consisting essentially of a small amountof an emulsifier, about 25% to about 33% of a hard asphalt in an aqueousphase in the form of roundedsolid asphalt particles separated from thecontinuous aqueous phase by an interfacial film and about 16% to about25% of .a lower melting solid asphalt likewise dispersed in an aqueousphase in the form of rounded particles separated from the continuousphase by an interf'acial film, the hard asphalt andthe lower meltingasphalt being dispersed in the same aqueous phase whereby theinterfacial films on the hard asphalt particles and the lower meltingasphalt particles respectively prevent the fluxing of the hard asphaltwith the lower melting asphalt prior to the breaking of the emulsion.

KARL DAIMLER.

